Electric toothbrushes having a head with a rotating working element in the form of a single cylindrical brush or in the form of a pair of brushes are becoming an increasingly common hygiene tool allowing effective removal of deposits from teeth.
For proper and effective teeth cleaning, including spaces in between teeth, it is necessary to apply the movement of the toothbrush head in a direction such that the bristles move in a rotating manner from the gums towards the biting edge of the teeth.
During the cleaning of the front and rear tooth surfaces and of the upper and lower jaw teeth, the rotating movement of the brush has to be reversed; thus, known toothbrushes are equipped with technical means that enable said change of the rotation direction.
Known toothbrushes of such kind typically contain a handle with extending head, said head having at its end a rotating cylindrical brush or a pair of brushes rotating in opposite directions.
Known toothbrushes typically contain driving motors, electric power sources, and electric equipment inside the handle, said equipment allowing at least to switch the motor on and off. The neck part of said toothbrushes contains an element linking the motor with the rotating brush head.
A number of such devices have been presented in patent literatures. As an example, an electric toothbrush known from the description of the U.S. Patent Application Publication No. 2008052845 is equipped with two brushes with parallel rotation axes, allowing to simultaneously brush both sides of the teeth in a direction form the gum line toward the teeth crowns. To reduce a possible injury of the inner cheek said brushes are partially covered with a casing. The toothbrush is additionally equipped with a manual switch to turn on and change the rotation direction of said brushes.
Another electric toothbrush, described in U.S. Pat. No. 4,163,300, includes an elongated body member having a cylindrical brush mounted coaxially therewith at one end thereof. The brush is driven in a rotatable way by a reversible electric motor located in the handle and having an automatic reversing weight-driven switch responsive to the position in which the handle is held to cause rotation of the brush such that its bristles move in a direction from the gum line towards the crowns of the teeth.
A toothbrush with a gravitation-driven switch of the direction of rotation of the brush, is known from the description of the U.S. Pat. No. 4,709,438, said toothbrush having a headpiece with a cylindrical brush and a handle. The cylindrical brush is located coaxially with respect to the handle. By means of a gravity switch, the direction of the rotation of the brush is reversed according to the turning movement of the handle in order to automatically maintain a direction of the rotation of the brush from the gums to the crown of the teeth. In order to obtain the correct position of the toothbrush, the brush is provided with a protecting cap leaving an opening allowing to form a working zone. The gravity switch is arranged parallel to the plane of the working zone of the brush.
From the description of the German utility model NO. DE 20321083U, an electric toothbrush is known containing a handle and a headpiece with a cylindrical brush rotating in two opposite directions. The rotation direction of the brush can be changed with a manual switch. The rotating brush is coupled with an electric motor by the shaft and toothed gear or belt transmission. The headpiece is located eccentrically to the longitudinal axis of the handle and a shield attached to the head surrounds more than a half of the brush ambit. As a result, when used, the brush is placed horizontally such that the direction of its movement is consistent with the orientation of the teeth and the gaps between the teeth.
An automatic toothbrush as claimed in the European Patent Application NO. EP 0240469 has a cylindrical paintbrush-like rotor able to rotate in opposite directions selected by an automatic control unit. The brush is located coaxially to the longitudinal axis of the handle. The change of the brush rotation direction is obtained with two opposite longitudinal edges of a shell which partially covers the swab-like rotor and is rotatably mounted to the handle. When one edge of the shell gets in contact with the gums or the tooth, the shell forced by the pressure rotates with respect to the handle, moving the contacts of the rotation direction switch.
In the U.S. Pat. No. 5,794,296, an electric toothbrush is disclosed having a rotary brush located coaxially to the longitudinal axis of the handle. The direction of the rotation of the brush is automatically controlled depending on whether the top or the bottom teeth are being brushed, in order to brush any food debris present on the teeth and gums in a direction away from the gums. The toothbrush according to this invention utilizes a direction controller that is placed inside the mouth between the top and bottom teeth. The direction controller switches the direction of brush rotation and serves to stabilize the toothbrush relative to the teeth during the brushing operation. The rotation of the direction controller with respect to the handle, operates a reversing switch to change the direction of rotation of the brush, as required to brush in a direction away from the gums and towards the teeth, without removing the toothbrush from the mouth. The direction controller is a narrow frame-shaped element oriented along the generating line of the cylindrical brush and attached rotatably with respect to the handle.
From the description of U.S. Pat. No. 3,829,922, an electric toothbrush is provided with a handle and coaxially located rotary brush, said brush being driven by a reversible electric motor placed inside the handle. The rotation direction of the electric motor is controlled by a reversing switch. For this purpose the toothbrush is equipped with a longitudinally extending shield located at the end of the control lever of the switch. Close to the opposite end, the lever is supported in the handle such that the pendulous movement of the lever with respect to the handle is possible in a plane substantially parallel to the axis of the brush rotation, from first active position—when the end of the shield is placed on one side of the brush and the brush is rotating in the first direction, through the neutral position—when the drive is switched off—until the second active position—when the end of the shield is placed on another side of the brush and the brush is rotating in the opposite direction. Movement of the shield away from the normal position, perpendicular to the rotation axis of the brush rotation in one or the other active position is transferred to the coupled end of the lever to the reversing switch to change the direction of the rotation of the motor and thereby the rotary brush. The return movement of the lever with attached shield to the neutral position, wherein the motor is switched off, is forced by the spring attached inside the handle and coupled to the lever.
From the description of French Patent No. FR 2891452, an electric toothbrush is provided with a cylindrical headpiece rotating in directions changed by the pressure force of the tooth directed obliquely with respect to the longitudinal axis of the handle. The toothbrush is equipped with a cylindrical brush designed to rotate away from the gums and towards the teeth. The brush, which is removable from the handle, is connected to gears with a shaft inside a casing, which forms the neckpiece of the toothbrush. Forced by the pressure of the headpiece on the teeth, the casing flips from one position to the other, causing its other end, projecting into the handle, to switch the contacts controlling the direction of the electric motor rotation. The casing is supported in a handle by a median pivot, allowing for the movement in a plane substantially parallel to the longitudinal axis of the handle, similarly to the guard lever of the headpiece known from the description of U.S. Pat. No. 3,829,922.
The rotating cylindrical brush is located at the end of the casing obliquely with respect to the longitudinal axis of the handle to enforce on the user proper placement during brushing. Particularly, the direction of the brush rotation is aligned with the orientation of the teeth and the gaps between the teeth, and simultaneously enables the inclination of the casing with respect to the handle, caused by the pressure force of the headpiece on the teeth, and to move the casing into position wherein the end of the casing placed inside the handle switches the contacts controlling the motor rotation direction, such that the brush rotates from the gums to the crown of the teeth.